The present invention relates to an improved gas furnace of the type which is suited for use in a recreational vehicle or similar environment. The furnace is gas-fired, uses gravity-fed (i.e., non-forced) through-the-wall combustion air, and employs a fan for circulating room air. No special ductwork is required for installation. Furnaces of this type are sometimes referred to as "undercounter" furnaces because they are designed to fit in small spaces such as are available beneath counter tops.
According to the present invention, a heat exchanger assembly for an undercounter furnace includes first and second complementary sidewalls made from sheet metal and shaped to provide a fire chamber. The sidewalls are mirror images of each other, and they are also shaped to provide an integral lower combustion air intake and upper exhaust flue. The sidewalls are flanged throughout their periphery so that they may be spotwelded together. In other words, the entire fire chamber, combustion air intake and exhaust are formed from two pieces of sheet metal. The heat exchanger is mounted on a removable chassis.
Adjacent the intake and exhaust conduits, the fire chamber is smoothly curved from the top of the combustion air intake to the bottom of the exhaust flue and the room air blower fan is located in the intermediate space between the combustion air intake and exhaust flue for forcing room air over both sides of the fire box, the width of which is less than its height and length. Thus, room air to be heated is uniformly swept across both sides of the fire box and then routed through a grille into the room to be heated.
A horizontal vent air terminal is provided on an outside wall adjacent the rear of the furnace; and as is conventional, the combustion air is taken in through an annular space about the exhaust flue which also extends through the air terminal. The combustion air is taken in through a vertical chamber at the rear of the furnace and routed to the lower combustion air intake leading to the fire box.
Room air to be heated is taken in through the bottom and sides of the grille and routed to the rear of the furnace where the fan forces it over the fire box. The fan is operated by a first heat sensing switch, and a second heat sensing switch limits the temperature of the discharged circulating room air to a maximum of 200.degree. F.
Other features and advantages of the present invention will be apparent to persons skilled in the art from the following detailed description of a preferred embodiment accompanied by the attached drawing wherein identical reference numerals will refer to like elements in the various views.